MATLAB Constraint Solver. MATLAB Constraint Solver

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1 MATLAB Constraint Solver i

2 Copyright Vitech Corporation. All rights reserved. No part of this document may be reproduced in any form, including, but not limited to, photocopying, translating into another language, or storage in a data retrieval system, without prior written consent of Vitech Corporation. Restricted Rights Legend Use, duplication, or disclosure by the Government is subject to restrictions as set forth in subparagraph (c) (1) (ii) of the Rights in Technical Data and Computer Software clause at DFARS Vitech Corporation 2270 Kraft Drive, Suite 1600 Blacksburg, Virginia FAX: Customer Support: support@vitechcorp.com is a trademark of Vitech Corporation and refers to all products in the GENESYS software product family. Other product names mentioned herein are used for identification purposes only, and may be trademarks of their respective companies. Publication Date: May 2018 ii

3 TABLE OF CONTENTS PREFACE... vi CONSTRAINT DEFINITION IN GENESYS Constraint Block Definition Diagram... 1 PARAMETER DEFINITION IN GENESYS Defining Parameters Creating ConstraintDefinitions... 3 SOLVING EXPRESSIONS USING THE MATLAB CONSTRAINT SOLVER MATLAB Constraint Solver... 5 iii

4 LIST OF FIGURES Figure 1 MATLAB Constraint Solver Concept Graphic... vi Figure 2 Constraint Definition Schema Relations... 1 Figure 3 - Constraint Definition Property Page... 1 Figure 4 New Vehicle Constraint bdd... 2 Figure 5 - Updated Parameter Tab... 2 Figure 6 - Updated Parameter Definition... 3 Figure 7 - Total Vehicle Weight Attributes... 3 Figure 8 - Total Vehicle Weight with Mappings... 4 Figure 9 - Total Vehicle Weight parametric block diagram... 5 Figure 10 - Constraint Solver Command... 5 Figure 11 - Constraint Solver - 1st Dialog Box... 5 Figure 12 - MATLAB Constraint Solver 2nd Dialog Box... 6 Figure 13 - MATLAB Script Dialog Box... 6 Figure 14 - MATLAB Constraint Solver - Pending Execution... 7 Figure 15 - MATLAB Constraint Solver Results Dialog Box... 7 Figure 16 - MATLAB Solution - Updating Parameters... 8 Figure 17 - Parameter Value Version... 8 iv

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6 PREFACE The MATLAB Constraint Solver provides the ability to solve a set of parametric equations constraining the design of a system. The MATLAB Constraint Solver is integrated into GENESYS 6.0 and uses MATLAB Version 2015b or higher, to solve a selected set of ConstraintDefinitions determined by the user. The MATLAB Constraint Solver converts project relationships, parameter values, and attribute values into scripts that can be directly executed against the MATLAB engine without having to leave the GENESYS interface. Following script execution, project parameter values can be updated based on the MATLAB solution. An overview of the MATLAB Constraint Solver is shown in the following graphic. 1) Expressions are created in constraint definitions via dependent and independent variable attributes 2) Expressions use entity parameters as seed values via model relationships and relationship attributes 3) MATLAB scripts are created and the connector executes it to solve expressions 4) Expression results are used to assign the value of entity parameters via model relationships and relationship attributes Figure 1 MATLAB Constraint Solver Concept Graphic This guide describes the processes used to populate and model ConstraintDefinition entities, declare and populate parameters in Component and ConstraintDefinition entities, and solve a selected set of ConstraintDefinition expressions using the MATLAB Constraint Solver. This guide is intended to augment the Model-Based Systems Engineering (MBSE) with GENESYS training course and the reference material provided with GENESYS. The ultimate goal of this guide is to expose the user to the MATLAB Constraint Solver and thereby extend the use and application of GENESYS for system design, development, and project management associated with the system development project. The following additional resources are available for use with this guide: For descriptions of GENESYS, including database classes and folders, different views, diagram notation, and the mechanics of entering data into GENESYS, the reader is referred to the GENESYS Help and Documentation guide. For the definition of schema terms, the reader is referred to the GENESYS schema, which contains descriptions for each schema entity, associated attributes, and parameters. vi

7 For application of GENESYS to system and architecture design, the reader is referred to the GENESYS System Definition Guide (SDG) and Architecture Definition Guide (ADG) each of which is provided in the set of GENESYS documentation supplied when GENESYS is installed on a computer workstation or available on our website. vii

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9 CONSTRAINT DEFINITION IN GENESYS 1.1. Constraint Block Definition Diagram Utilizing the MATLAB Constraint Solver begins with defining constraints in the system design. The ConstraintDefinition captures the definition of parametric constraints as an expression (or equation) and identifies the independent variables and the dependent variable as attributes of the entity. The ConstraintDefinition is used in development of both the Constraint Block Definition Diagram and the Parametric Diagram in GENESYS. Generally, a ConstraintDefinition constrains a Component in the architecture. Relevant schema relations for the ConstraintDefinition are shown in the following diagram. Figure 2 Constraint Definition Schema Relations The ConstraintDefinition property page contains a unique set of attributes as shown in the diagram below. Figure 3 - Constraint Definition Property Page In the property page the Expression attribute is used to capture the constraint s mathematical equation(s) using independent variables and dependent variables. 1

10 From the perspective of a Component in the architecture, the constrained by relation is used to create the Constraint Block Definition Diagram (Constraint BDD). A ConstraintDefinition entity can use parameter from another Component. An example Constraint BDD for Component New Vehicle is shown below. Figure 4 New Vehicle Constraint bdd PARAMETER DEFINITION IN GENESYS 1.2. Defining Parameters The use of Component parameters is essential when managing and solving scripts derived from ConstraintDefinition models using the MATLAB Constraint Solver. The Parameters tab has been updated in GENESYS to expand the ability to identify and manage values. The updated Parameters tab is shown below. Figure 5 - Updated Parameter Tab The user can now define Objective, Threshold, Design, and Observed parameter values. The Objective value is used to capture the value nominally defined through a Requirement. The Design value is used to capture the calculated design value (the value determined using the MATLAB Constraint Solver). The Observed value is used to capture the value for the as built system. In addition to an updated parameter page, the ability to define a parameter has been revised. Parameters can now be copied from those defined in other classes of the project. Additionally, the definition page now 2

11 includes the ability to define an abbreviation for the parameter. The updated parameter definition dialog box is provided in the following figure. Figure 6 - Updated Parameter Definition 1.3. Creating ConstraintDefinitions As the system design evolves from the design requirement architecture through the functional architecture, the design team will allocate requirement constraints (and their related parameters) to components in the physical architecture. The design team will also identify constraint definitions for individual components in the architecture. A typical example is system weight. The overall system weight is a parameter that is tracked in the design. The overall system weight is a summation (or roll-up) for the weight of many individual components in the architecture. Therefore, we can define the system design weight as a constraint definition with an expression which adds the weight of several lower level components. Below is a constraint definition defining the Total Vehicle Weight for an automobile design. Figure 7 - Total Vehicle Weight Attributes 3

12 Once a ConstraintDefinition has been defined in the property sheet, the Independent Variables need to be associated with a parameter in the design. This is accomplished by relating the ConstraintDefinition with another entity in the architecture by establishing a uses parameter from or includes constraint definition relation. Each of these relations have a Mappings relationship attribute. The Mappings relationship attribute associates an individual Independent Variable with a parameter (uses parameter from) or a Dependent Variable (includes constraint definition) from the target entity. The Independent Variable will be seeded with the value of the parameter/dependent variable when the expression is evaluated using the MATLAB Constraint Solver. The Dependent Variable constrains an entity in the design. This is established using the constrains relation and the Mappings relation attribute. The value of the dependent variable is calculated in the solution, and this value is placed in the Design attribute for parameter mapped to the dependent variable. Using the example from the Total Vehicle Weight entity (shown in the prior diagram), the Independent Variable declared as W-curb takes its value from the parameter curbweight which has been defined and associated with the Component SYS.1 Vehicle Frame. Independent Variables take their value from the Design Parameter value as a priority. If the Design value is nil, then the value is taken from the Objective value. The Dependent Variable W-total constrains the Component SYS New Vehicle, and the value (which will be calculated by the MATLAB Constraint Solver) will be associated with the totalvehicleweight parameter. The relations and configurations of Mappings relationship attributes for Total Vehicle Weight are shown in the Targets & Attributes section of an entity property page. An example is shown below. Figure 8 - Total Vehicle Weight with Mappings The relation and its attributes are also displayed graphically in the parametric diagram for the ConstraintDefinition. The preferred way to set the Mappings relationship attribute is by using the Edit Mappings command on the parametric diagram when you have a line selected. 4

13 Figure 9 - Total Vehicle Weight parametric block diagram SOLVING EXPRESSIONS USING THE MATLAB CONSTRAINT SOLVER 1.4. MATLAB Constraint Solver The Project ribbon in GENESYS contains the button used to execute the MATLAB Constraint Solver. Figure 10 - Constraint Solver Command When the Constraint Solver command is selected, a MATLAB Constraint Solver dialog box is opened in GENESYS. This is the first step in a series of dialog boxes that walk the user through the process of using the constraint solver. The first dialog box allows the user to select one or more ConstraintDefinitions that have been collected in a folder, package, or contained in a diagram. Figure 11 - Constraint Solver - 1st Dialog Box 5

14 Depending on the selection made in the first dialog box, the user will be directed to a second dialog box to select a particular ConstraintDefinition, folder, or package. The example below shows the selection options taken when using the Selected ConstraintDefinition option from the 1 st dialog box. Figure 12 - MATLAB Constraint Solver 2nd Dialog Box In the example above, the user is selecting the ConstraintDefinition Total Vehicle Weight as the entity to be solved. Once a selection is made, selecting Next brings up the MATLAB script box (the 3 rd dialog box in the execution sequence). This box shows the parameters mapped to the ConstraintDefinition, as well as the expression and dependent variable mappings that will be used to create the script to be solved by MATLAB. Figure 13 - MATLAB Script Dialog Box The user can review the parameters, parameter values, and the expression and dependent variables being used prior to solving the script. The script can be saved as a text file if desired. When ready to complete the solution, the user will select the Next button to execute the MATLAB Constraint Solver. Selecting the Next button will change the dialog box to show the MATLAB script results with a solution. The script box will indicate (pending script execution), as shown below. 6

15 Figure 14 - MATLAB Constraint Solver - Pending Execution Selecting the Execute script button from this page will execute the scripts against MATLAB s solver engine and calculate the value for the dependent parameter(s) in the ConstraintDefinition. After execution the solved parameter value is shown below. Figure 15 - MATLAB Constraint Solver Results Dialog Box Following script execution, the Update parameters button can be used to place the parametric value into the appropriate Design column for the respective parameter. If a parametric value has a new (or updated) value, the dialog box will indicate that the parameter has been updated, as shown below. 7

16 Figure 16 - MATLAB Solution - Updating Parameters If the user then navigates to the updated parameter, the original value and the updated value (the value that has changed based on the MATLAB Constraint Solver solution) will be shown. Figure 17 - Parameter Value Version 8

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